Hydrocyclone 1

For the second design, I wanted to learn to use the software package Autodesk Fusion 360. I decided to use Autodesk Fusion 360, as it is free for students and is extremely intuitive for beginners. After getting to grips with the software, I generated a design specifically created for 13mm piping which we have in the labs. The design was quite simply influenced by the shapes of other hydrocyclones seen on the internet. Unfortunately, the 3D printer printed support structures on the interior of the hydrocyclone which were impossible to remove (note to self, always check where the printer will print support structures). Thankfully, I did learn from this model that the inlets were marginally too small for the piping and I was afraid of leakages, so I went away and made the design slightly larger in order to ensure a tight fit. To prevent the support structures from affecting the interior of the cyclone, I split the design into four seperate components which I plan to glue together using Loctite Ultra Control Gel. I chose to use Loctite Ultra Control Gel following some brief research into the most effective adhesives for PLA plastic. Ideally, I would have used a 3D printer that can print dissolvable, PVA support structures so I could have printed the hydrocyclone as a single piece.

After gluing together the hydrocyclone - which went exactly as I had planned, thankfully - I realised that to achieve the desired vortex I needed a more powerful pump than the peristaltic pump we have in the labs. My initial idea was to source a pond pump from an aquatics supplier, however to achieve the desired 800ml/s (approximately), I would need a pump that would cost somewhere in the region of £120. Unfortunately this meant that the hydrocyclone was pretty much useless. The only testing I was feasibly able to accomplish was running a tap through the cyclone to explore whether the volume of underflow still vastly exceeded the volume of overflow. Literature suggests that the ratio of overflow to underflow should be approximately 80:20. Annoyingly, the overflow:underflow ratio was closer to 20:80 with this cyclone. Because of this minor set back, I went back to the drawing board to work on Hydrocyclone 2.

Hydrocyclone 2

Design adaptations

After stumbling across a paper titled The Sizing and Selection of Hydrocyclones by Richard A. Arterburn, I was able to design the hydrocyclone with much clearer direction. For example, I have shortened the cyclindrical feed chamber to promote the development of the inner cyclone. To futher promote this development, I have also extended the length of the vortex finder. In order to solve the flow rate problem, I have designed hydrocyclone #3 to be much smaller; the total volume is now 20cm^{3} as opposed to the volume of hydrocyclone #2, which had a total volume of 100cm^{3} . However, I still wanted this design to be able to seperate slightly larger particulate contaminants from water, such as sand, so I had to ensure that the inlet and outlets were large enough to prevent clogging.

After the initial testing of Hydrocyclone 2 revealed an overflow:underflow volume ratio of 42:100 (an improvement on Hydrocyclone 1, but still not sufficient), I went back to reading literature, seeking instruction on how to adapt the design to increase overflow output.

Hydrocyclone 3

Design adaptations

After the initial testing of Hydrocyclone #3 revealed an overflow:underflow volume ratio of 42:100 (an improvement on Hydrocyclone #2, but still not sufficient), I went back to reading literature, seeking instruction on how to adapt the design to increase overflow output. The paper: Hydrocyclones for Particle Size Separation (J. J. Cilliers, 2000) recommended increasing the angle of the conical chamber from the cylindrical feed chamber from 20^{\circ} to 30^{\circ}. It was also suggested that I change the diameter of the vortex finder, as diameter of the vortex finder should not equal the diameter of the spigot (underflow outlet). It is suggested that the size of the spigot should be within the range 0.1-0.2\ D c while the size of the vortex finder should be within the range 0.13-0.43\,Dc. I also adapted the inlet feed so that it was rectangular as opposed to circular. In the image it looks square, however that opening tapers down to a rectangle with a height to width ratio of 2:1 (still tangential to the cyclindrical feed chamber).

Initial testing of the Hydrocyclone was to discover whether the perfect overflow to underflow ratio of 80:20 could be achieved at a particular flow rate. After some initial optimisation of flow rates, I discovered that the perfect ratio could be achieved with a flow rate of 143ml/s. The experiment I conducted was to connect the cyclone to the pump, and run the experiment until the overflow outlet had been filled to 1L. My results then showed that at 143ml/s, for every litre of overflow, I had 250ml of underflow (give or take 5ml). The experiment was conducted three times and an average was taken. The next round of experimentation will follow the protocol as detailed above. I will be testing the hydrocyclone's ability to actually filter larger particulates from the water.

Lab Protocol

Below is the lab protocol I have written for the next round of experimentation:

You will need:

• Hydrocyclone 3.
• DC pump, capable of flow rates of up to 1200L/H.
• (Some sort of stirring device to keep the aragonite sand in suspension)
• Necessary tubing.
• Aragonite sand solution with a sand to water ratio of 20:80.
• Seives with a mesh small enough to filter aragonite sand from the underflow (approx 100 microns).
• 3 x 5-litre beakers/buckets.
• heavy duty scales + a set of more sensitive scales for measuring the volume of sand.
• Stopwatch

Set up of the experiment:

1. Weigh out 1kg of aragonite sand and pour into the sample solution beaker. Then fill the beaker to the 5L marker with water.
2. While turned off, and unplugged, place the DC pump in the sample solution, being careful not to get the electrical components wet. Ensure that the pump is flat on the bottom of the beaker.
3. Set up a clamp stand over the 'Underflow beaker' and secure the hydrocyclone vertically.
4. Connect the necessary tubing; pump to inlet feed, vortex finder to overflow beaker, spigot to underflow beaker. Use tie wraps to secure.
5. Give the sample solution a good stir and be prepared to quickly begin the experiment while the sand is still in suspension.
6. Before conducting the experiment, ensure that the stopwatch is to hand.

Protocol (read carefully before continuing):

1. Instantaneously turn on the DC pump and initialise the stopwatch.
2. (BEFORE THE WATER LEVEL FALLS BELOW THE PUMP INLET) Turn off the pump and stop the stopwatch. Record the time.
3. Use the seive to filter out the aragonite sand from the underflow while keeping the water in a measuring container. Note the volume of water.
4. Dry the remaining sediment in an oven.
5. Using the scales, measure the weight of the underflow sediment. Note the ratio of underflow sand:water.
6. Repeat this step for the overflow.